Unloader for compressor



April 22, 1958 HARTWELL 2,831,625

UNLOADER FOR COMPRESSOR Filed June 29, 1956 GEORGE W. HARTWEL L HERBERT E. LINDNER INVENTORS United States Patent UNLOADER FOR COMPRESSOR George W. Hartwell and Herbert E. Lindner, South Hadley, Mass., assiguors to Worthington Corporation, Harrison, Y. J., a corporation of Delaware Application June 29, 1956, Serial No. 594,994

2 Claims. (Cl. 230-24) The present invention relates to a compressor and more particularly to a compressor provided with means for varying the capacity thereof.

In fluid compressors designed to operate at relative constant speed, the load on the system in which the compressor is arranged may sometimes vary, resulting in an inefiicient operation of the compressor unless the capacity of the compressor can be varied with these system variations.

In accordance with the present invention, is provided having novel means for unloading the compressor to vary the output thereof which meets the changing requirements of the system in which it is arranged and thereby results in a considerable saving in operating power.

The present invention provides an unloading means for a compressor having electromagnetic'means for unloading the compressor wherein the coil of the electromagnetic means is at no time exposed to the pumped gas, thus eliminating possible coil deterioration due to reaction with the gas, and eliminating the need for sealing of electrical leads into the electromagnet.

The present invention further provides an electromagnetic unloader for a compressor wherein a non-magnetic insert is used to guide the flux through the unloader valve to increase the magnetic force of the electromagnet and obtain the desired lifting and holding ability thereof.

The present invention further provides an electromagnet unloader for a compressor which is merely exposed to the pressure and temperature of conditions ambient to the compressor head resulting in an electromagnet having a coil which may be used over a long period of time.

The invention will be better understood from the following description when considered in connection with the accompanying drawing forming a part thereof and showing a fragmentary sectional View of a compressor embodying the unloader of the present invention.

Referring to the drawing, the reference numeral designates a compressor having a reciprocating piston 11 disposed in a cylinder 12 with a cylinder head 13 comprising a lower plate member 12a and an upper cover member 13a bolted to the compressor frame to close off the upper end of the cylinder.

The enlarged upper end of cylinder 12 is provided with a plurality of vertical ports or passageways 14 drilled in the circumference thereof and spaced at intervals from one another to form inlets for refrigerant gas to be compressed in the cylinder. An annular ring 15 composed of a magnetic or conductive material such as steel forming a suction valve is disposed in a recess 16 in the cylinder above inlet ports 14 and is adapted to seat over the inlet ports to control the flow of gas therethrough.

An annular ring 17 forming a discharge valve is mounted on plate member 12a and is adapted to seat over a plurality of vertical outlet ports or passageways 18 disposed therein in communication with cylinder 12.

a compressor Discharge ports 18 are arranged in a circle in the plate member and communicate with a discharge chamber 19 disposed in cover member 13a for discharging compressed refrigerant gas thereto. Ring 17 is normally maintained in a seated or closed position by an annular resilient ring 20 disposed thereabove having a plurality of depending fingers or cars 21 extending downwardly therefrom. A bored spacer member 20a is maintained between the plate and cover members for spacing ring 20 the desired position above ring 17.

The unloader of the annular coil 23 disposed in an annular recess 26 in plate member 12a between the inner and outer annular segments 27 and 28 thereof and having electrical conduits 24 and 25 extending transversely through segment 28 and connected to a source of winding or electrical power (not shown). It will be noted coil 23 is L-shaped in cross-section to establish distinct magnetic poles. An annular insert member 29 made of non-magnetic or nonconductive material is positioned in the cylinder head between segments 27 and 28 and 'between magnetic coil 23 and annular ring 15 forming the suction valve for the cylinder so that the incoming refrigerant gas to be compressed in the cylinder never contacts the magnetic coil, thus preventing deterioration thereof due to reaction with the gas. The provision of the non-conductive insert member 29 guides the flux from the coil when it is energized to the annular ring 15 by decreasing the width of the flux path and thereby concentrating it to intensify the effective force of the electromagnet in unseating the annular ring 15. A return spring 30 in the form of a flat annular resilient ring is disposed in recess 16 above the annular ring 15 to maintain this annular ring seated over inlet passageways 14 when the coil 23 is not energized. Resilient ring 30 is normally arced in a vertical plane but when the magnetic coil 23 is energized, as shown in the accompanying drawing, to unload the compressor cylinder 12 it assumes a flat shape.

In operation, when the unloader of the present invention is not in use downward movement of the piston 11 in the cylinder will create a vacuum therein so that gas to be compressed entering inlet passageways 14 will lift the annular ring 15 off its seat overcoming the force in ring 30 tending to keep it seated and permit the gas to flow into the cylinder. Thereafter, when piston 11 moves upwardly in the cylinder, the gas therein is compressed and lifts discharge valve or ring 17 off its seat to open discharge outlet 18 so that the gas may be discharged into the cylinder discharge chamber 19. Ring 30 will seat annular ring 15 to close inlet ports 14 at this time.

When it is desired to unload the compressor cylinder 12 the magnetic coil 23 is energized and a concentrated flux path is created in members 27 and 28 on either side of the non-magnetic insert member 29 disposed therein to lift the annular ring 15 from its seated position and maintain inlet passageways 14 open. This allows gas to pass into the cylinder on the intake stroke of piston 11 and to be discharged from the suction passageways 14 on the discharge stroke of the piston, thus making the compressor cylinder inoperative as far as the compressing of gas is concerned and thereby enabling the compressor to vary its output capacity.

It will be understood that the invention is not to be limited to the specific construction and arrangement of parts shown but they may be widely modified within the invention defined by the claims.

What is claimed is:

1. In a compressor including at least one compression cylinder, a piston disposed for reciprocating movement in said cylinder, an annular valve in one end of said cylinder adapted to unload the compressor, and a cylinder head Patented Apr. 22, 1958 present invention comprises an disposed on said one, end of said cylinder'and adapted to house an electromagnet for operating saidgannulan valve, said cylinder head comprising a plate member and a cover member, said plate member having an annular recess coaxial with said annular valve for housing the electromagnet and a central passageway spaced inwardly of said annular recess in communication with the cylinder for discharging fluids from the said cylinder,and said cover member having a central discharge chamber in communication with said central discharge passageway and an outer portion concentric to said discharge chamber adapted to fit over said plate member to thereby form a closure for the annular recess housing the electromagnet preventing contact between the said electromagnet and the fluids discharging from the cylinder.

2.'The cylinder head housing the electromagnet as claimed in claim 1 wherein the electrical conduits of said electromagnet extend outwardly therefrom transversely through the plate member preventing contact between the said electrical conduits and the fluids discharging from the cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 1,713,234 Litle May 14, 1929 1,762,544 Cadman June 10, 1930 2,245,053 Sanders June 10, 1941 2,302,847 Ferguson Nov. 24, I942 2,454,976 Ploeger Nov. 30, 1948 2,626,099 Ashley Ian. 20, 1953 

